A wide variety of glass, metal and plastic containers are used to hold, store and ship liquids, including beverages. Manufacturers apply labels to the containers for informational, marketing and advertising purposes. Labels in various forms also are applied to a variety of surfaces, including but not limited to windows, doors, tires and vehicles, for similar reasons.
Originally, paper was the most common substrate used for labels. Subsequently, several types of clear or translucent plastic, polyolefin, or polymer labels (i.e., “film labels”) were created. The use of film labels has increased because the appearance when applied to a glass or plastic surface or container simulates “painted glass” so as to provide something approaching a “no label” look. The objective is to have the text and graphics on the label appear to be painted directly on the surface or container itself. In addition, clear film labels when used on containers allow consumers to see the beverage, liquid or product in the container, to the extent the container itself allows. Some marketing studies indicate that consumers seem to prefer being able to see the beverage in the container.
With respect to the beverage industry today, there are two common forms of applying labels to containers: the “cut-and-stack” method; and the pressure sensitive method. In the cut-and-stack method, labels typically are attached to containers using water-based glue or adhesive and standard cut-and-stack labeling equipment, such as equipment manufactured by Krones or Phoenix Manufacturing. Adhesive is dispensed and metered by a glue roller, and transferred to glue pallets. A stack of pre-cut labels is inserted into the labeling machine, and are removed one at a time from the stack by the glue pallets, which apply the adhesive on the glue pallet to the back of the label. The label is then positioned on the container, and the labeler performs a series of wiping actions to ensure that the glue is uniformly spread and the label is adhered to the container. The water base of the adhesive evaporates through the label or from around the edges of the label, allowing the adhesive to dry and thereby securing the label to the container.
The cut-and-stack method works well with paper-based labels because the water base of the adhesive can evaporate through the porous paper substrate of the label. Film labels generally are not made of a porous material, however, thus preventing this form of evaporation. When using film labels for cut-and-stack labels, label producers typically print the text and graphics on the outer or “first” surface of the film. In order to allow the water in the adhesive a path to “escape”, a hydrophilic, glue-receptive coating may be applied to the “second” (inner or container-side) surface of the film label. The hydrophilic coating serves as an attachment layer for the adhesive, while the film label serves as a barrier to protect the printed inks on the outer surface from the caustic, water-based adhesive.
At present, the most common clear film labels for surfaces and containers are pressure sensitive, or self-adhesive, labels. In the pressure sensitive method, a film label manufacturer produces a laminated substrate comprising a clear film layer (which will become the label), a pressure sensitive adhesive layer, a silicone release coating layer, and a backing (liner) film. Because the pressure sensitive label stock is a laminated structure, label producers typically print on the outer or first surface of the clear film layer.
With both methods, the first surface of the label usually is exposed to scuffing during the production process, and during shipping and handling. As a result, label producers must use inks and coatings formulated with additives for scuff resistance. These additives typically reduce the opacity of the inks, however, resulting in degraded aesthetics unless multiple layers of ink are applied, thus increasing production costs. In addition, if a glossy label is desired, the producer must use inks formulated with gloss additives. These additives further reduce the opacity of the inks. As a result, many manufacturers of pressure sensitive labels use slow, rotary screen presses that apply a thick layer of ink to the first or outer surface of the film layer.
In addition, clear or solid color film labels do not achieve a satisfactory “no label look.” Gas bubbles or glue voids form between the label and the bottle. And clear or solid color films still are readily distinguishable from the underlying container.
Thus, what is needed is an inexpensive, easy-to-manufacture film label that protects the printed image on the label from abrasion or scuffing, can be used in any clear film label application, and produces a satisfactory “no label look.” In addition, what is needed is a label coating that can be used with clear film and opaque film labels to achieve satisfactory application to surfaces.